html {
    width: 100%;
    body {
        width: 100%;
        .index {
            max-width: 750px;
            min-width: 300px;
            width: 100%;
            margin: 0 auto;
            position: relative;
            overflow: hidden;
            .btn {
                width: 92%;
                letter-spacing: 0.2em;
                padding-left: 2%;
                line-height: 2.5;
                margin: 0.3rem auto;
                font-size: 0.48rem;
                color: #fff;
                text-align: center;
                background-color: #009688;
                border-radius: 5px;
            }
        }
    }
}